Olefin-containing fuel gas may be upgraded to gasoline using a Mobil Olefins to Gasoline (“MOG”) process. In this process, a fluidized bed reactor containing a catalyst, such as ZSM-5, receives the fuel gas feed and oligomerizes olefins in the fuel gas to produce C5+ gasoline. Catalyst particles are circulated to a regenerator to burn the coke that is formed during the oligomerization reactions. Typically, multiple times the stoichiometric air requirement (i.e., a theoretical excess amount of air) is fed to the regenerator to maintain the desired superficial velocity in the regenerator, to achieve a desirable vessel diameter, and to achieve the complete combustion of coke. The reason this is so, is because, the coke make in the MOG process as a wt % of the feed olefins, is less when compared to conventional fluid catalytic cracking units.